Procedure:

1. Preheat oven to 180C/gas. Roll out the pastry and use it to line a 23cm greased tart tin. Cover with baking paper, fill with dried beans and bake blind for 10-15 minutes, remove beans and bake again for 15 minutes until golden. 2. Put the cream, sugar and salt in a pan and bring to a boil. Remove as soon as the mixture boils up. Off the heat, add the butter and chocolate. Stir until blended. 3. Take a couple of minutes for a breather, then stir in the milk. Keep stirring till shiny. Pour into the tart shell and leave at room temperature for 2 hours to set. 4. Sprinkle salt flakes lightly all over, then serve with creme fraīche or whipped cream.